cmpmacchia

Is the 3.8 liter a 90 or 60 degree V6?
I believe the 3.7 liter engines in the liberty are 90 degree.
Does the angle have any effect on engine idol (smooth/ rough)?

Red

The 3.8l V6 has a 60° V angle. It is based off of Chrysler's 3.3l engine that hit the market in the early 90's. This engine was Chrysler's first V6 that was developed as a V6 and not based off of a V8, i.e. brand new milling process, hence the 60° as opposed to the 90° that you normally see on a V8 based V6.

The Jeep Liberty has a 3.7l engine with a 90° V angle. This engine is based off of Chrysler's Power Tech engine. In other words it is derived from a 4.7l V8, and comes from the same machining process. Since a 90° V angle is perfect for a V8, the V6 engines coming off the same line retain the 90° V angle.

Does the V angle have anything to do with how smooth the engine runs? In short, yes, but in combination with other aspects of the engine. The crankshaft has a lot to do with it as well. A 3 throw and 6 throw crank will have a different effects on the smoothness, as will the incorporation of flying arms. How the engine is mounted in the vehicle makes a huge difference as well. A V6 with a 60° V slant can be made pretty smooth with little difficulty. 60 is after all half of 120, which is the natural angle for a V6. For that matter, you can also balance a V6 with a 90° V angle as well using offset split crankpins to even out the firing interval. Bottom line is, the V6 will not be as smooth as an inline 6, but I'm sure the engineers over at Chrysler figured out how to make the engine run smooth enough that most people won't notice a difference between it and a straight 6 in terms of smoothness.

pearl-drum-man

I can definitely say the 3.8L in the JK is smoother than the 3.7L in my fiances '06 Liberty. I can also say that the 3.7L seems much more responsive, despite being only rated for slightly more HP.

RedneckJeep

It is unfortunate for power, that's it's a 60 degree. I must say though, as time goes on that I am very happy with mine. It does a good job. Even if it does just sit inside my shop 95% of the time now.

jkkat

I have RubyDoo (2007 jeep wrangler rubicon) and Daphanie (2004 dodge dakota 3.7 5speed) they both do ok but Daphanie does a little better as far as power in the low end range and does not rev up as far as RubyDoo.

cmpmacchia

Personally I'm glad the 3.8 is a 60 degree. The engine is much smoother than the 3.7 in the liberty (90 degree). I hated how the liberty shook at idle.
The liberty did have more punch though.

cucmd1

If the 3.7 was an option i definitely would have chose it over the 3.8. Our liberty feels powerful not just adequate. As I'm breaking in the 3.8 it's getting better (3200 miles now), but the wrangler really is a pig. (I love it and won't be getting trading it, but it is a pig).

RedneckJeep

Imagine though if Chrysler had put the 3.9 from the Dakota in the Jeep. THAT would have been a powerful V6. All it is is a 318 with 2 cylinders hacked off.

jfreeddo

would the 3.7L V6 be the same one from the Dodge Ram 1500 pickups. if so, I wasn't any more impressed with it that I am with my JK. It was louder, more rough, not any more fuel efficient, and put any more weight into the back of the truck and it felt like a 4 cyl. I have pulled the same trailer and load with that truck and now with the JK and Jk did just as well as far as power, even on the low end, now handling and suspension with the same load probably went to the truck but that's a whole different ballgame.

cmpmacchia

My 2005 liberty was a bigger pig on fuel!